1. Field of the Invention
This invention relates to orthopaedic braces, and, in particular, to orthopaedic braces that include an inflatable air bag wrapped around a joint or appendage supported by the brace and responsive to an abnormal condition capable of injuring the joint or appendage.
2. Description of the Prior Art
Orthopaedic braces are typically used to provide additional support to a joint that, due to prior injury, defect, surgery or other cause, does not provide normal support or that limits the normal range of motion of a limb connected to the joint. For example, the knee brace invented by us and disclosed in U.S. Pat. No. 5,133,341, herein included by reference, provides support for the knee without undue restriction on the natural kinematics of the knee. The brace includes a rigid posterior strut located in the popliteal space of the knee to which vertical supports are connected by hinges. Application Ser. No. 07/861,722, filed Apr. 1, 1992, to issue as U.S. Pat. No. 5,267,946 and herein included by reference, discloses a similar type of knee brace that can be adjusted to fit knee joints of different sizes and shapes. These braces are very useful for prophylactic, functional and rehabilitative purposes. However, these braces and other types of passive restraint braces do not include any mechanism that would protect against an abnormal, severe, lateral or torsional force, stress, strain or acceleration that can potentially cause further injury to the joint, or protect against tearing of the muscle connected to the joint, except for the normal travel limits of extension and flexion.
Inflated air bags, or air cells, can provide a high degree of support to protect against such potentially injury causing conditions. Some types of braces include inflatable air bags surrounding selected portions of the joint to provide support to the joint. U.S. Pat. No. 4,872,448, to Johnson, Jr., discloses a knee brace with a U-shaped inflatable air cell engaging the knee above and along opposed sides of the patella. The air cell is inflated to a desired pressure and remains in that condition during use. U.S. Pat. No. 5,125,400, also to Johnson, Jr., discloses an ankle brace having multiple inflatable cells that are inflated during use of the brace. However, because the air cells of these devices remain inflated during use, the range of motion of the joint supported by the brace is reduced (for high inflation of the air cells) or the brace provides limited support in response to an excessively stressful condition (for low inflation of the air cells).
There are also a variety of safety devices that include air cells that inflate in response to a potentially injury-causing condition. U.S. Pat. No. 5,133,084, to Martin, discloses an inflatable safety collar device for use primarily by motorcyclists. Inflation is triggered by a pull string which may be attached to a vehicle for operation during a crash or collision. U.S. Pat. No. 4,984,821, to Kim et al., discloses a suit to be worn by motorcyclists that has air cells contained between the layers of cloth in the pants and jacket. Similar to Martin, the air cells are inflated when a pull string attached to the vehicle is tensioned. These devices fail to provide support for a joint during normal use. Needless to say, the above-described collar and suit become awkward to wear if the rider forgets to disengage the pull cord before dismounting the vehicle.
Therefore, there is a need for an orthopaedic brace that provides support to a joint and full, normal range of movement during normal use, and that also provides additional support to the joint in response to an excessive force, stress, strain or acceleration that may otherwise injure the joint.
There is an additional need for a brace that can quickly stimulate muscles connected to the joint in response to an excessive lateral or torsional force, stress, strain or acceleration to preload the muscle in preparation for the excessive condition and thereby avoid possible damage to the muscle.